Front or rear brake rotors, brake pad wear sensors

Hot Tip:

Clean brake caliper

Performance Gain:

Proper brake function

Complementary Modification:

Flush brake fluid. Replace brake pads

BMW Z4 service brakes consist of hydraulic brake calipers and rotors, one at each wheel. When the brake pedal is pressed, brake fluid is forced out of the brake master cylinder and through the brake lines to each brake caliper. Pistons in the calipers push out and clamp brake pads against the brake rotors (or discs), thus slowing down the vehicle. A vacuum assisted brake booster multiplies the braking force exerted by the driver at the brake pedal.

You should check your brake rotors with every major service that you perform on your BMW Z4. Inspect your brake rotors for cracks, scoring or replace if you have a pulsation when braking. Brake rotors can look OK and still be worn out. If there is a ridge around the edge of the brake rotor, this is a good sign that they are worn out. Measure brake rotor thickness using a micrometer to determine if they need replacing. When measuring, measure in a few different spots and use lowest number. The minimum allowable thickness of a rotor is stamped on the edge of the rotor.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please include your vehicle information.

Using a flathead screwdriver, slowly press brake caliper piston in. This allows brake caliper to be pulled off brake rotor easily. I like to pry between the outer brake pad and brake rotor. This way there is less chance of damaging the caliper piston. Forcing the piston back into the caliper will cause the brake fluid in the reservoir to rise. Be prepared to remove some fluid.

Front: Next, using a 6mm Allen bit, remove brake rotor mounting fasteners (red arrows). Then remove brake rotor from hub. The rotor might be stuck so be prepared to give it a few taps with a mallet. If you are replacing the rear rotor make sure the parking brake is off before trying to remove the rotor.

Front: Next, using a 6mm Allen bit, remove brake rotor mounting fasteners (red arrows). Then remove brake rotor from hub. The rotor might be stuck so be prepared to give it a few taps with a mallet. If you are replacing the rear rotor make sure the parking brake is off before trying to remove the rotor.